From: Edward Balow (ebalow@hotmail.com)
Date: Mon Apr 14 2008 - 09:20:17 ART
BGP is one way to ensure that you can use the same IP address space with
multiple providers. Without BGP, if you have circuits from two providers,
each will give you its own IP space for your use. Assume you have a corporate
Web server. Without BGP you could assign two IP addresses to the web server,
and/or do some NATting or Dynamic DNS to provide failover. With BGP, you get
to use a single IP address for your web server that both ISPs can route to.
BGP is often used just for this--to provide inbound redundancy over two
service providers. This is the simplest configuration.
There are products and technologies to get a single IP to work without BGP.
But BGP is the native way to do it.
It can also be used outbound as well, but this can be more complicated. When
using BGP for outbound path selection, one will generally download the entire
BGP table (hundreds of megs) to their router and set priority to impact which
circuit is used. For example, say ISP1 provides better service to Europse and
ISP2 provides better service to Asia.
And then there's the option to set yourself up as a transit path (traffic not
sourced or destined to you, just passing through your link) which is generally
a very bad idea unless you are an ISP.
Ed
> Date: Mon, 14 Apr 2008 17:33:23 +0530> From: jeniferdcosta@gmail.com> To:
sadiqtanko@gmail.com> Subject: Re: Can anybody explain me when we should use
bgp and when we should not> CC: yemi.salau@siemens.com;
ccielabs@groupstudy.com; ccielab@groupstudy.com> > Hi Sadik,> > Can u be more
explanatary in detail for me,i know this everybody says when u> r dual homed
to an isp then use BGP but i want to know with proper> explanation.> > On Mon,
Apr 14, 2008 at 3:28 PM, Sadiq Yakasai <sadiqtanko@gmail.com> wrote:> > >
Fundamentally, BGP is to be used as a protocol when your network is> > dual
homed to either a single ISP or two (or more) ISPs.> >> > Sadiq> > > Pass the
CCIE in six weeks, Guaranteed!> http://www.certscience.com/CCIE>
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